System, Method and Apparatus for Supporting Guardrail Posts

ABSTRACT

The present invention provides a system, method and apparatus for supporting guardrail posts. The system includes a foundation tube, a guardrail post partially disposed within the foundation tube, and a spacer disposed between the guardrail post and the foundation tube. The spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.

FIELD OF THE INVENTION

The present invention relates generally to the field of transportation safety and, more particularly, to a system, method and apparatus for supporting guardrail posts.

PRIORITY CLAIM TO RELATED APPLICATIONS

This patent application is a non-provisional application of U.S. provisional patent application 60/830,954 filed on Jul. 14, 2006 and entitled “System, Method and Apparatus for Supporting Terminal Posts” which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION

Wooden guardrail posts have been used along highways and roads for many years. More recently, wooden guardrail posts have been replaced with Steel Yielding Terminal Posts (SYTP) in foundation tubes during repair, replacement or maintenance of the wooden posts. The SYTP is also used as an alternative to Breakaway Cable Terminal (BCT) posts in foundation tubes. In addition, SYTPs are often used instead of wooden guardrail posts or BCT posts in new installations. A SYTP can be directly embedded in soil or inserted into a foundation tube. The foundation tubes are nominally 6 inch by 8 inch rectangular steel sleeves that provide additional resistance to movement of the guardrail post when the guardrail is struck by an errant vehicle. The foundation tubes also facilitate the rapid replacement of posts after an impact.

Referring now to FIG. 1, an illustration of a SYTP 100 within a foundation tube 102 is shown in accordance with the prior art. A one inch schedule 40 pipe is used as a spacer 104 to hold the SYTP 100 in the foundation tube 102. A bolt 106 is used to position the SYTP 100 and secure it to the foundation tube 102 via holes 108, 110 in the foundation tube 102 and holes 112, 114 in the SYTP 100. The one inch schedule 40 pipe spacer 104 backs up one side of the compression flange of the foundation tube 102. Under dynamic loading, this SYTP configuration caused premature buckling of the SYTP 100 due to non-symmetric loading of the compression flange. As a result, this design is not functional for the SYTP 100.

Accordingly, there is a need for new spacer that allows the installation of steel breakaway posts as substitutes for wooden breakaway posts in steel foundation tubes. Moreover, there is a need for a spacer that can be used in new, replacement or retrofit barriers to improve the performance characteristics of such barriers.

SUMMARY OF THE INVENTION

The present invention provides a system, method and apparatus for supporting guardrail posts. The spacer, also referred to as a block, spacer block or retrofit spacer block, which allows the use of breakaway guardrail posts, such as the steel yielding terminal posts, line posts, length of need posts and so forth, in foundation tubes that were previously used to provide support for wooden breakaway posts. The spacer can also be used in new installations. The spacer provides full support of the compression flange of the post during impact, allows full strength of the post to be developed and limits the movement of the steel post in the foundation tube. In addition, the spacer can be used in new, replacement or retrofit barriers to improve the performance characteristics of such barriers. The barriers can be of any type, such as a box-beam barrier, a cable barrier, a Thrie-beam barrier, a W-beam barrier or a combination thereof.

More specifically, the present invention provides a system that includes a foundation tube, a guardrail post partially disposed within the foundation tube, and a spacer disposed between the guardrail post and the foundation tube. The spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.

The present invention provides a spacer having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of a foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of a guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.

The present invention also includes a method that includes the steps of inserting a guardrail post in a foundation tube and inserting a spacer between the terminal post and an inner wall of the foundation tube. The spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.

In addition, the present invention provides a kit for securing a guardrail post partially disposed within a foundation tube. The kit includes a spacer having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension, and a fastener to secure the terminal post and the spacer in place within the foundation tube.

The present invention is described in detail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings, in which:

FIG. 1 depicts several views of a Steel Yielding Terminal Post mounted within a foundation tube in accordance with the prior art;

FIG. 2 depicts several views of a guardrail post mounted within a foundation tube with a spacer block in accordance with one embodiment of the present invention;

FIGS. 3A, 3B and 3C depict spacer blocks in accordance with various embodiments of the present invention;

FIGS. 4A and 4B are accelerometer and force traces for a test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil;

FIGS. 5A and 5B are accelerometer and force traces for another test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil;

FIGS. 6A and 6B are accelerometer and force traces for another test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil;

FIGS. 7A and 7B are accelerometer and force traces for a test of Steel Yielding Terminal Post mounted within a foundation tube in accordance with the prior art;

FIGS. 8A and 8B are accelerometer and force traces for a test of Steel Yielding Terminal mounted within a foundation tube with a spacer block in accordance with one embodiment of the present invention;

FIG. 9 depicts several views of a Cable Barrier mounted within a foundation tube with two spacer blocks in accordance with one embodiment of the present invention;

FIG. 10 depicts several views of a Thrie-beam Barrier mounted within a foundation tube with a spacer block in accordance with one embodiment of the present invention;

FIG. 11 depicts several views of a W-beam Barrier mounted within a foundation tube with a spacer block in accordance with one embodiment of the present invention;

FIG. 12 depicts several views of a guardrail post mounted within a foundation tube integrated in a mow strip with a spacer block in accordance with one embodiment of the present invention;

FIG. 13 depicts several views of a wooden post within a foundation tube or shaft with a spacer block in accordance with one embodiment of the present invention;

FIG. 14 depicts several views of a guardrail post mounted within a circular foundation tube or shaft with a spacer block in accordance with one embodiment of the present invention; and

FIG. 15 depicts a flow chart of a method of installing a spacer block in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. The discussion herein relates primarily to the support of Steel Yielding Terminal Posts (SYTP), but it will be understood that the concepts of the present invention are applicable to any traffic safety related barriers.

The present invention provides a spacer, also referred to as a block, spacer block or retrofit spacer block, which allows the use of breakaway steel guardrail posts, such as the SYTP, in foundation tubes that were previously used to provide support for wooden breakaway posts. The spacer can also be used in new installations. The spacer provides full support of the compression flange of the post during impact, allows full strength of the post to be developed and limits the movement of the steel post in the foundation tube. In addition, the spacer can be used in new, replacement or retrofit barriers to improve the performance characteristics of such barriers. The barriers can be of any type, such as a box-beam barrier, a cable barrier, a Thrie-beam barrier, a W-beam barrier or a combination thereof.

The present invention is discussed in terms of guardrail posts; however, the skilled artisan will recognize that the term guardrail posts as used herein may be used interchangeably with the terms: terminal posts, line posts, length of need posts, steel yielding line posts, steel yielding terminal posts or other posts serving a similar function. In addition, the guardrail posts may be of varying size, shape, height, diameter and be constructed from various materials, e.g., wood, metals, steel, alloys, composites, plastics and so forth.

Referring now to FIG. 2, an illustration of a SYTP 100 within a foundation tube 102 with a spacer block 200 in accordance with one embodiment of the present invention is shown. A SYTP 100 (also referred to interchangeably as posts, guardrail posts or terminal posts) is partially disposed within a foundation tube 102. The foundation tubes 102 are typically a substantially rectangular sleeve having a cross section dimension of approximately 6 inches by 8 inches that provide additional resistance to movement of the guardrail post when the guardrail is struck by an errant vehicle. Alternatively, the foundation tube can have a cross section that is substantially circular, square, rectangular or other geometrical shape. The foundation tubes 102 also facilitate the rapid replacement of posts after an impact. In addition, the foundation tube can be integrated into a mow strip or be formed by a shaft formed in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof. A spacer 200 is used to hold the SYTP 100 in the foundation tube 102. The spacer 200 will be further described in reference to FIGS. 3A, 3B, 3C, 13 and 14.

A bolt or other fastener 106 known by those skilled in the art to be suitable for such an installation is used to position the SYTP 100 and secure it to the foundation tube 102 via holes 108, 110 in the foundation tube 102, holes 112, 114 in the SYTP 100 and hole 202 in the spacer block 200. Holes 108, 110, 112, 114 and 202, or other suitable aperture known by those skilled in the art to be suitable for such an installation are aligned in the foundation tube 102, the SYTP 100 and the spacer 200 so that the fastener 106 passes through the series of aligned apertures 108, 110, 112, 114 and 202. Note that the fastener 106 can be integrated into the spacer as shown in FIGS. 3B and 3C. The spacer block 200 backs up one side of the compression flange of the foundation tube 102.

Now referring to FIG. 3A, a spacer 200 in accordance with one embodiment of the present invention is shown. The spacer addresses the deficiencies of the prior art by providing full support of the compression flange. The spacer 200 is disposed between the SYTP or guardrail post 100 and the foundation tube 102 and has overall dimensions of approximately (a) a first dimension 204 that is smaller than a first interior dimension 116 of the foundation tube 102, (b) a second dimension 206 that is equal to or less than a second interior dimension 118 of the foundation tube 102 less an exterior dimension of the SYTP 100 and (c) a third dimension 208 greater than or equal to one half of the first dimension 204. For example, the first dimension 204 can be approximately 5.5 inches, the second dimension 206 can be approximately 1.25 inches and the third dimension 208 can be approximately 5.5 inches. The spacer 200 can be made of high density, high molecular weight polyethylene (e.g., PE 3408), wood, metal, elastomer, honeycomb, plastic, other material known by those skilled in the art to be suitable for such an installation or a combination thereof. Some of these alternatives, such as elastomers and honeycomb may have the added advantage of dissipating energy and permitting more deflection of the post during redirection impacts. The spacer 200 includes a hole or aperture 202 to receive a fastener 106. For example, the hole or aperture 202 can be a one inch diameter hole located 1.25 inches from a top of the spacer 200 and centered from side to side. Another alternative embodiment is an injection molded piece that may eliminate the need for a post bolt. The injection molded piece would have extensions that would insert in the ground-line holes of the SYTP 100 and then either wedge against the foundation tube (FIG. 3B) or hang on the foundation tube (FIG. 3C).

Referring now to FIG. 3B, a wedge-shaped spacer 300 in accordance with another embodiment of the present invention is shown. The spacer 300 is disposed between the SYTP or guardrail post 100 and the foundation tube 102 and has overall dimensions of approximately (a) a first dimension 302 that is smaller than a first interior dimension 116 of the foundation tube 102, (b) a second dimension (bottom) 304 and (top) 306 that are less than and greater than, respectively, a second interior dimension 118 of the foundation tube 102 less an exterior dimension of the SYTP 100 and (c) a third dimension 308 greater than or equal to one half of the first dimension 302. For example, the first dimension 302 can be approximately 5.5 inches, the second dimension (bottom) 304 and (top) 306 can be approximately 0.75 to 1.00 inches and 2.215 inches, respectively, and the third dimension 308 can be approximately 5.5 inches. Instead of using a fastener, spacer 300 includes a channel 310 to receive the SYTP or guardrail post 100 and extensions 312 to engage corresponding ground-line apertures or holes in the SYTP or guardrail post 100 and rounded edges 314 to form a frictional fit with the foundation tube 102. For example, the extensions 312 can be between 0.313 and 0.438 inches in diameter and located 0.917 inches from a top of the spacer 300 and 1.50 inches from each side.

Now referring to FIG. 3C, a block 350 in accordance with another embodiment of the present invention is shown. The spacer 350 is disposed between the SYTP or guardrail post 100 and the foundation tube 102 and has overall dimensions of approximately (a) a first dimension 352 that is smaller than a first interior dimension 116 of the foundation tube 102, (b) a second dimension (bottom) 354 and (top) 356 that are less than and greater than, respectively, a second interior dimension 118 of the foundation tube 102 less an exterior dimension of the SYTP or guardrail post 100 and (c) a third dimension 358 greater than or equal to one half of the first dimension 302. For example, the first dimension 352 can be approximately 5.5 inches, the second dimension (bottom) 354 and (top) 356 can be approximately 1.375 to 1.625 inches and 2.125 inches, respectively, and the third dimension 308 can be approximately 5.5 inches. Instead of using a fastener, spacer 350 includes a channel 360 to receive the SYTP or guardrail post 100 and extensions 362 to engage corresponding ground-line apertures or holes in the SYTP and rounded edges 364 to form a frictional fit with the foundation tube 102. Spacer 350 also includes a lip 366 that extends over the edge of the foundation tube 102. For example, the extensions 312 can be between 0.313 and 0.438 inches in diameter and located 0.50 inches from a top of the spacer 350 and 1.50 inches from each side.

The present invention also includes a method that includes the steps of inserting a terminal post in a foundation tube, inserting a spacer between the terminal post and an inner wall of the foundation tube, and securing the terminal post and spacer to the foundation tube. The spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the terminal post and (c) a third dimension greater than or equal to one half of the first dimension. The terminal post, foundation tube and spacer can be SYTP or guardrail post 100, foundation tube 102 and spacer 200, 300 or 350 as previously described.

In addition, the present invention provides a kit for securing a terminal post partially disposed within a foundation tube. The kit includes a spacer having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the terminal post and (c) a third dimension greater than or equal to one half of the first dimension, and a fastener to secure the terminal post and the spacer in place within the foundation tube.

The performance of the spacer has been shown, through a pendulum test, to provide the needed support that allows the full strength of the SYTP to be developed when impacted in the strong axis. The spacer will allow substitution of the SYTP for current wooden breakaway posts in foundation tubes. The SYTP post was tested using a pendulum bogie, built according the specifications of the Federal Outdoor Impact Laboratory's (FOIL) pendulum. Frontal crush of the aluminum honeycomb nose of the bogie simulates the crush of an actual vehicle and the sweeper plate, constructed of steel angles and a steel plate, is attached to the body of the pendulum with a ground clearance of 152 mm to replicate roughly an automobile's undercarriage. The crushable nose configuration is the FOIL ten stage bogie nose. Cartridges of expendable aluminum honeycomb material of differing densities are placed in a sliding nose. After a test, the honeycomb material is replaced and the bogie is reused. Testing was performed in accordance with NCHRP Report 350 and as briefly described below.

The bogie was instrumented with two accelerometers mounted at the rear of the bogie to measure longitudinal acceleration levels. The accelerometers were strain gage type with a linear millivolt output proportional to acceleration. The electronic signals from the accelerometers were amplified and transmitted to a base station by means of constant bandwidth FM/FM telemetry link for recording on magnetic tape and for display on a real-time strip chart. Calibration signals were recorded before and after the test and an accurate time reference signal was simultaneously recorded with the data. Pressure sensitive switches on the nose of the bogie were actuated by wooden dowel rods and initial contact to produce speed trap and “event” marks on the data record to establish the exact instant of contact with the installation, as well as impact velocity.

The multiplex of data channels, transmitted on one radio frequency, were received at the data acquisition station, and demultiplexed into separate tracks of I.R.I.G. tape recorders. After the test, the data were played back from the tape machines, filtered with an SAE 1211 filter and digitized using a microcomputer, for analysis and evaluation of impact performance. A proprietary software program (WinDigit) converts the analog data from each transducer into engineering units using the R-cal and pre-zero values at 10,000 samples per second, per channel. WinDigit also provides SAE J211 class 180 phaseless digital filtering and bogie impact velocity.

The Test Risk Assessment Program (TRAP) uses the data from WinDigit to compute occupant/compartment impact velocities, time of occupant/compartment impact after bogie impact, and the highest 10-ms average ridedown acceleration. WinDigit calculates change in bogie velocity at the end of a given impulse period. In addition, maximum average accelerations over 50-ms are computed. For reporting purposes, the data from the bogie-mounted accelerometers were then filtered with a 180 Hz digital filter and plotted using a commercially available software package (Microsoft EXCEL).

Referring now to FIGS. 4A and 4B, accelerometer and force traces for a test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil are shown. The pendulum bogie, traveling at 35.0 km/h (21.8 ml/h) impacted the direct buried SYTP post at 0 degree along the weak axis. Shortly after impact, the post deformed rearward and the honeycomb in the nose of the pendulum began to crush. At 0.074 s, the pendulum lost contact with the post, and the pendulum was traveling at an exit speed of 33.1 km/h (20.6 ml/h). Change in velocity was 0.5 m/s (1.8 ft/s). Peak acceleration was −4.2 g's, and peak force was 34.60 kN (7.78 kips). The notches in the base of the post at ground level were torn on the impact side, and the post was leaned over but remained intact on the side opposite impact. Total crush of the pendulum honeycomb was 101 mm (4.0 inches).

Now referring to FIGS. 5A and 5B, accelerometer and force traces for another test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil are shown. The pendulum bogie, traveling at 35.1 km/h (21.8 ml/h) impacted the direct buried SYTP post at 0 degree along the strong axis. Shortly after impact, the post deformed rearward and the honeycomb in the nose of the pendulum began to crush. At 0.044 s, the post began to rotate, and at 0.242 s, the pendulum lost contact with the post, and the pendulum was traveling at an exit speed of 23.8 km/h (14.8 ml/h). Change in velocity was 3.1 m/s (10.3 ft/s). Peak acceleration was −10.4 g's, and peak force was 85.19 kN (19.15 kips). The notches in the base of the post at ground level were torn on the impact side and on one side on the side opposite impact. The post was rotated slightly and deformed. Total crush of the pendulum honeycomb was 281 mm (11.1 inches).

Referring now to FIGS. 6A and 6B, accelerometer and force traces for another test of Steel Yielding Terminal Post embedded in NCHRP Report 350 standard soil are shown. The pendulum bogie, traveling at 35.0 km/h (21.8 ml/h) impacted the direct buried SYTP post at 0 degree along the strong axis. Shortly after impact, the post deformed rearward and the honeycomb in the nose of the pendulum began to crush. At 0.101 s, the pendulum lost contact with the post, and the pendulum was traveling at an exit speed of 19.0 km/h (11.8 ml/h). Change in velocity was 4.4 m/s (14.7 ft/s). Peak acceleration was −9.6 g's, and peak force was 78.78 kN (17.71 kips). The post was rotated slightly to the right and deformed to the field side 90 mm (3.5 inches). Total crush of the pendulum honeycomb was 250 mm (9.8 inches).

Now referring to FIGS. 7A and 7B, accelerometer and force traces for a test of Steel Yielding Terminal Post mounted within a foundation tube in accordance with the prior art (FIG. 1) are shown. In this test, a 22 mm (⅞-inch) diameter hole was drilled in the flange of the SYTP that allowed the placement of a 16 mm (⅝-inch) bolt through the post and foundation tube. A 25 mm (I-inch) long, 25 mm (I-inch) diameter schedule 40 pipe spacer was used to position the SYTP in the foundation tube. In test P7, the SYTP was impacted in the weak direction and activation of the SYTP was similar to previous tests with the SYTP embedded in NCHRP Report 350 standard soil. When the same system was impacted in the strong direction, the non-symmetric support, the pipe spacer on one flange, caused a premature lateral torsional buckling of the SYTP post.

The pendulum bogie, traveling at 35.0 km/h (21.8 ml/h) impacted the SYTP post in a foundation tube at 0 degree along the weak axis. Shortly after impact, the post deformed rearward and the honeycomb in the nose of the pendulum began to crush, and at 0.034 s, the weakened points (reduced cross-section because of holes) in the base of the post fractured. At 0.242 s, the pendulum lost contact with the post, and the pendulum was traveling at an exit speed of 30.2 km/h (18.8 ml/h). Change in velocity was 1.3 m/s (404 ft/s). Peak acceleration was −604 g's, and peak force was 52.69 kN (11.85 kips). The notches in the base of the post at ground level were torn on the impact side, and the post was leaned to the left but remained intact on the side opposite impact. Total crush of the pendulum honeycomb was 107 mm (4.2 inches).

Referring now to FIGS. 8A and 8B, accelerometer and force traces for a test of Steel Yielding Terminal mounted within a foundation tube with a spacer in accordance with one embodiment (FIG. 2) of the present invention are shown. For the test, a 32 mm (1.25 inch) thick, 140 mm×140 mm (5.5 inch×5.5 inch) HDPE spacer was installed between the SYTP and the foundation tube. The pendulum bogie, traveling at 34.6 km/h (21.5 ml/h) impacted the SYTP post in a foundation tube with an HDPE spacer block at 0 degree along the strong axis. Shortly after impact, the post deformed rearward and the honeycomb in the nose of the pendulum began to crush. The foundation tube began to push rearward through the soil at 0.038 s, and the top of the post began to rotate away from the pendulum at 0.084 s. At 0.180 s, the pendulum lost contact with the post, and the pendulum was traveling at an exit speed of 17.5 km/h (10.8 ml/h). Change in velocity was 4.8 m/s (15.7 ft/s). Peak acceleration was −9.8 g's, and peak force was 80.25 kN (18.04 kips). The post was rotated slightly to the left and deformed to the field side 55 mm (2.2 inches). The right front hole was torn and all others were intact but deformed. Total crush of the pendulum honeycomb was 311 mm (12.2 inches). In both strong and weak axis directions, the post failure modes were similar in both the direct embedded and foundation tube spacer retrofit. The SYTP in the foundation tube with the HDPE spacer block performed similar to the direct embedded SYTP. The peak acceleration on the strong axis SYTP in foundation tube was 9.8 g's and the peak values for the direct embedded tests was 10.4 g's and 9.6 g's respectively.

Referring now to FIG. 9, several views of a Cable Barrier mounted within a foundation tube 102 with two spacer blocks 200 in accordance with one embodiment of the present invention are shown. A modified SYTP 900 (also referred to as posts or terminal posts) is partially disposed within a foundation tube 102. The foundation tubes 102 are typically a substantially rectangular sleeve that provides additional resistance to movement of the guardrail post when the cable barrier is struck by an errant vehicle. Alternatively, the foundation tube can have a cross section that is substantially circular, square, rectangular or other geometrical shape. The foundation tubes 102 also facilitate the rapid replacement of posts after an impact. In addition, the foundation tube can be integrated into a mow strip or be formed by a shaft formed in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof. The cable barrier is formed by installing one or more cables 902 (typically three cables) in slots 904 within the modified SYTP 900. The cables 902 are held in place with one or more straps 906 and cable spacers 908. Two spacers 200 on either side of the modified SYTP 900 are used to hold the SYTP 900 in the foundation tube 102. The spacer 200 can be of the type described in reference to FIGS. 3A, 3B, 3C, 13 and 14. Moreover, one or more fasteners can be used to secure the modified SYTP 900 and spacers 200 to the foundation tube. The fasteners are not required.

Other examples of the spacers 200 being used with terminal posts 100 in various types of barriers are shown in FIGS. 10-12. FIG. 10 shows a Thrie-beam 1000 barrier. FIG. 11 shows a W-beam 1100 barrier. FIG. 12 show a W-bean 1100 with block out 1200 integrated into a mow strip 1202, which is typically concrete.

Now referring to FIG. 13, several views of a wooden post 1300 within a foundation tube 102 or shaft with a spacer block 1306 in accordance with one embodiment of the present invention are shown. A wooden post 1300 (also referred to as posts or terminal posts) is partially disposed within a foundation tube 102. The foundation tubes 102 are typically a substantially rectangular sleeve that provides additional resistance to movement of the guardrail post when the cable barrier is struck by an errant vehicle. Alternatively, the foundation tube can have a cross section that is substantially circular, square, rectangular or other geometrical shape. The foundation tubes 102 also facilitate the rapid replacement of posts after an impact. In addition, the foundation tube can be integrated into a mow strip or be formed by a shaft formed in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof. Alternatively, the foundation tube is a shaft formed in rock 1302, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof that is filled in with a suitable filler material after installation of the wooden post 1300. In either case, a spacer 1304 is disposed within the foundation tube 102 or the shaft near ground level 1306. The spacer 1304 may or may not be secured to the wooden post 1300 with one or more fasteners.

Referring now to FIG. 14, several views of a guardrail post 100 mounted within a circular foundation tube 102 or shaft with a spacer block 1400 in accordance with one embodiment of the present invention are shown. A guardrail post 100 is partially disposed within a foundation tube 102. The foundation tube 102 in this case is circular and provides additional resistance to movement of the guardrail post when the cable barrier is struck by an errant vehicle. The foundation tubes 102 also facilitate the rapid replacement of posts after an impact. In addition, the foundation tube can be integrated into a mow strip or be formed by a shaft formed in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof. Alternatively, the foundation tube is a shaft formed in rock 1302, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof that is filled in with a suitable filler material after installation of the terminal post 100. In either case, a spacer 1400 is disposed within the foundation tube 102 or the shaft near ground level 1306. The spacer 1400 may or may not be secured to the terminal post 1400 with one or more fasteners.

Referring now to FIG. 15, a flow chart of a method 1500 of installing a spacer block in accordance with one embodiment of the present invention is shown. A foundation tube is provided in block 1502. This step is optional. The foundation tube can be provided by forming a hole to receive the foundation tube, installing the foundation tube within the hole and filling any space between an exterior of the foundation tube and the hole. Alternatively, the foundation tube can be provided by forming a shaft in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof. A guardrail post is inserted in the foundation tube in block 1504. A spacer is inserted between the guardrail post and an inner wall of the foundation tube in block 1506. The spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the terminal post and (c) a third dimension greater than or equal to one half of the first dimension. The spacer 200 can be of the type described in reference to FIGS. 3A, 3B, 3C, 13 and 14. The guardrail post and the spacer are secured to the foundation tube using one or more fasteners in block 1508. This step is optional. A filler material is added to the foundation tube in block 1510 such that the portion of the guardrail post and the spacer disposed within the foundation tube are surrounded. This step is optional.

Although, the foundation tube is discussed in terms of having a circular shape, a rectangular shape or square shape, the skilled artisan will recognize that the foundation tube may have other shapes, e.g., oval shaped, polygonal shaped, triangular shaped, rectangular shaped, circular shaped, free form shaped, or shapes made from a combination of different shapes.

Although preferred embodiments of the present invention have been described in detail, it will be understood by those skilled in the art that various modifications can be made therein without departing from the spirit and scope of the invention as set forth in the appended claims. 

1. A system comprising: a foundation tube; a guardrail post partially disposed within the foundation tube; and the spacer disposed between the guardrail post and the foundation tube and having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.
 2. The system as recited in claim 1, further comprising: a fastener securing the guardrail post and the spacer in place within the foundation tube; and a series of aligned apertures in the foundation tube, the guardrail post and the spacer wherein the fastener passes through the series of aligned apertures.
 3. The system as recited in claim 1, wherein: the foundation tube comprises a substantially rectangular sleeve having a cross section dimension of approximately 6 inches by 8 inches; the guardrail post comprises a steel yielding guardrail post; and the spacer comprises a block wherein the first dimension is approximately 5.5 inches, the second dimension is approximately 1.25 inches and the third dimension is approximately 5.5 inches.
 4. The system as recited in claim 1, wherein the spacer is made of high density, high molecular weight polyethylene, wood, metal, elastomer, honeycomb, plastic or a combination thereof.
 5. The system as recited in claim 2, wherein the aperture in the spacer comprises a one inch diameter hole located 1.25 inches from a top of the spacer and centered from side to side.
 6. The system as recited in claim 1, wherein the spacer is tapered, wedge-shaped, shaped substantially as shown in FIG. 3A, shaped substantially as shown in FIG. 3B, shaped substantially as shown in FIG. 3C, shaped substantially as shown in FIG. 13, or shaped substantially as shown in FIG.
 14. 7. The system as recited in claim 1, further comprising a filler material disposed within the foundation tube and surrounding the portion of the terminal post and the spacer disposed within the foundation tube.
 8. The system as recited in claim 1, wherein: the foundation tube is integrated into a mow strip; or the foundation tube has a cross section that is substantially circular, square, rectangular or other geometrical shape; or the foundation tube comprises a shaft formed in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof.
 9. The system as recited in claim 1, wherein: the guardrail post comprises a steel yielding terminal post, a wooden guardrail post or a breakaway cable terminal post; or the guardrail post forms part of a box-beam barrier, a cable barrier, a Thrie-beam barrier, a W-beam barrier or a combination thereof.
 10. A method comprising the steps of: inserting a guardrail post in a foundation tube; and inserting a spacer between the guardrail post and an inner wall of the foundation tube, wherein the spacer has overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.
 11. The method as recited in claim 10, further comprising the step of securing the guardrail post and the spacer to the foundation tube using a fastener.
 12. The method as recited in claim 10, further comprising the step of adding a filler material to the foundation tube such that the portion of the guardrail post and the spacer disposed within the foundation tube are surrounded.
 13. The method as recited in claim 10, further comprising the step of providing the foundation tube.
 14. The method as recited in claim 13, wherein the step of providing the foundation tube comprises the steps of: forming a hole to receive the foundation tube; installing the foundation tube within the hole; and filling any space between an exterior of the foundation tube and the hole.
 15. The method as recited in claim 13, wherein the step of providing the foundation tube comprises the step of forming a shaft in rock, concrete, asphalt, compacted soil, frozen soil, rocky soil or a combination thereof.
 16. The method as recited in claim 10, wherein: the foundation tube comprises a substantially rectangular sleeve having a cross section dimension of approximately 6 inches by 8 inches; the guardrail post comprises a steel yielding terminal post; and the spacer comprises a block wherein the first dimension is approximately 5.5 inches, the second dimension is approximately 1.25 inches and the third dimension is approximately 5.5 inches.
 17. The method as recited in claim 10, wherein the spacer is made of high density, high molecular weight polyethylene, wood, metal, elastomer, honeycomb, plastic or a combination thereof.
 18. The method as recited in claim 10, wherein the spacer further comprises a one inch aperture located 1.25 inches from a top of the spacer and centered from side to side.
 19. The method as recited in claim 10, wherein the spacer is tapered, wedge-shaped, shaped substantially as shown in FIG. 3A, shaped substantially as shown in FIG. 3B, shaped substantially as shown in FIG. 3C, shaped substantially as shown in FIG. 13, or shaped substantially as shown in FIG.
 14. 20. An apparatus comprising a spacer having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of a foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of a guardrail post and (c) a third dimension greater than or equal to one half of the first dimension.
 21. The apparatus as recited in claim 20, further comprising an aperture in the spacer to receive a fastener.
 22. The apparatus as recited in claim 20, wherein: the foundation tube comprises a substantially rectangular sleeve having a cross section dimension of approximately 6 inches by 8 inches; the guardrail post comprises a steel yielding terminal post; and the spacer comprises a block wherein the first dimension is approximately 5.5 inches, the second dimension is approximately 1.25 inches and the third dimension is approximately 5.5 inches.
 23. The apparatus as recited in claim 20, wherein the spacer is made of high density, high molecular weight polyethylene, wood, metal, elastomer, honeycomb, plastic or a combination thereof.
 24. The apparatus as recited in claim 21, wherein the aperture comprises a one inch diameter hole located 1.25 inches from a top of the spacer and centered from side to side.
 25. The apparatus as recited in claim 20, wherein the spacer is tapered, wedge-shaped, shaped substantially as shown in FIG. 3A, shaped substantially as shown in FIG. 3B, shaped substantially as shown in FIG. 3C, shaped substantially as shown in FIG. 13, or shaped substantially as shown in FIG.
 14. 26. A kit for securing a guardrail post partially disposed within a foundation tube, the kit comprising: a spacer having overall dimensions of approximately (a) a first dimension that is smaller than a first interior dimension of the foundation tube, (b) a second dimension that is equal to or less than a second interior dimension of the foundation tube less an exterior dimension of the guardrail post and (c) a third dimension greater than or equal to one half of the first dimension; and a fastener to secure the guardrail post and the spacer in place within the foundation tube.
 27. The kit as recited in claim 26, further comprising an aperture within the spacer that aligns with corresponding apertures in the foundation tube and the guardrail post to receive the fastener.
 28. The kit as recited in claim 26, wherein the spacer comprises a block wherein the first dimension is approximately 5.5 inches, the second dimension is approximately 1.25 inches and the third dimension is approximately 5.5 inches.
 29. The kit as recited in claim 26, wherein the spacer is made of high density, high molecular weight polyethylene, wood, metal, elastomer, honeycomb, plastic or a combination thereof.
 30. The kit as recited in claim 27, wherein the aperture in the spacer comprises a one inch diameter hole located 1.25 inches from a top of the spacer and centered from side to side.
 31. The kit as recited in claim 26, wherein the spacer is tapered, wedge-shaped, shaped substantially as shown in FIG. 3A, shaped substantially as shown in FIG. 3B, shaped substantially as shown in FIG. 3C, shaped substantially as shown in FIG. 13, or shaped substantially as shown in FIG.
 14. 